Lift the bonnet and underneath on either side you will see a U shaped metal loop with an adjusting nut to raise or lower them. They will adjust the height at which the catches engage but you will also need to adjust the bump stops or the bonnet may be hard to close, again there is one on each side at the front with a locking nut.
Look on the underside of the bonnet when you lift it up. The adjustable catches on either side are approx. 12" in from the side and 3" in from the front edge of the bonnet. They are painted black. The metal loop is threaded on one side with adjustment provided by a nut.